Who believes in a "break in" period?

[Klaus]

Hey guys,

 

Do any of you guys break in a fresh rebuild, as in not ride hard until the motor has run a tank or two of fuel? I rebuilt my top end, it ran for a couple of minutes, just for me to check everything was running good, then I took her for a dyno and rode hard the next day. I believe that as long as a engine is on operating temp, it can run hard, if you take the simple example, a piece of cold steel will snap if bent, but heat that same piece of steel up and you can bend it back and forth...

 

I read an article on some or other website that rings only have a certain time period in which they can seat, this is just after the rebuild. On the website it is said that on a engine which runs hard just after being rebuilt, the rings tend to seat better because the hone marks on the cylinders are "sharp" enough to make the rings seat. Once the hone marks have been worn down it takes longer for the rings to seat and they tend to not seat as well as a engine which has been run hard from the start.

 

Another thing, will sprockets influence a dyno readout? Some people say yes, some say no. Some say torque will be influenced but not hp.

 

What do you guys think bout these two topics??

 

[brugal]

I break - in the engine alot different then you discribed. But I do ride the shee full throttle at some point in the break-in.

[ned]

http://www.mototuneusa.com/break_in_secrets.htm

 

pretty much what ive followed for the last 12 engines ive had to rebuild and havent had a problem

 

[Klaus]

Ned thats the exact website I was referring to, thanks man. Any comments on the gearing and dyno?

[ned]

i dont think it would effect it that much due to the fact that a dyno dosent just get its readings from roller speed.

 

if i were you i would ride the bike around, get your desired gearing and then hit the dyno. that way you know your power at your normal riding conditions

[dirtydownunder]

gearing does effect dyno read out, so if you want to see if you have made more or less power on the same dyno you should use the same gearing.

 

 

[Klaus]

Cos I'm running a 12/41 sprocket setup and make 52 hp on the dyno. But my gears are so short I run the engine into the "over rev" zone in 6th very easily. I actually have to back off the throttle for a bit, then I can open up again. When I'm WOT in 6th he my friend shifts to 4th, haha, but that said he is running 16/41. I bought a 14 t front sprocket, it must just go on. He made 69 on the same dyno, but his shee is ported and running domes etc. I just have a stock RD motor.

 

I must take the bike back, she is running very rich and has a bog just under the powerband.

[dirtydownunder]

you will make less power if you go to the 14t front sprocket.

[TwistedSheeRida]

Breaking in a motor is just heating the rings then letting them cool. when i break in a motor i wont let the motor lug at all keep it in high rpms its better to over rev than to lug the motor during break in. for the first couple runs get it hot than let it cool so you can put your hand on the cylinders or pipe. the more times you heat the motor and cool it down the better you are. i rode mine all night the day i broke it in just ran it for like 15 mins than cool it for the same. works mint everytime.

[2001Stroker]

All I ever do is, 3 heat cycles, ride easy for 10 minutes, then ride the bitch.

[BoostedRex]

http://www.mototuneusa.com/break_in_secrets.htm

 

pretty much what ive followed for the last 12 engines ive had to rebuild and havent had a problem

 

Very good article. I have built numerous motors and used that theory on all of them for years. And my motors have always been the strongest running compared to my friends who do "soft" break in's.

[RagunCajun]

This is just opinions. Some people dont even break in their engines. Some builders just say ride it like you normally do. and sometimes the engines hold up fine.

[kawa110]

i didnt see aythig about 2-strokes in that article. it said for 4-stroke. Im getting ready to "break-in" or start since a new top end my 1978 yz250 2-stroke. I plan on using caster 927 with premium and mix a little rich. (this oil seems sticky and i feel it does well on my old parts by keeping em oily, I also love the smell)

I usually start, warm up, then take for a light spin, shut down cool off check for leaks maybe tune carb little. then ill repeat 2 more times each time riding little harder, but not revvin out. Usually about half tank of gas, then ill fill back up with normal mixture on the rich mix. And ill ride it tell that tank almost out, Before i put next tank in ill pull the spark plugs, and fine tune it all. On next tank ill fill up normal mix warm up and light spin if all is good ill ride hard.

[Klaus]

you will make less power if you go to the 14t front sprocket.

 

 

Dont you mean less torque? Or less power too?

 

Like I said above, I believe as long as an engine is on operating temp, it can be ridden hard. On a 4t oil temp must be warm, not just water temp. A lot of people differ with me, but everyone is entitled to his/her own opinion. Whatever works for you.

Edited June 7, 2009 by Klaus

[Bill]

Yea when I broke mine in last weekend I just did 2 heat cycles and retorqued everything.

 

Then I rode it easy for about 15 min to make sure everything was all good, then I gave her hell.